1. Field of the Invention
The present invention relates to regeneration apparatus and method for a particulate filter used for a post process of an exhaust gas of, mainly, a Diesel engine and an exhaust gas purifying device using the regeneration apparatus and method described above.
2. Description of the Related Art
A Diesel particulate filter is a particulate trap (or collection) device constituted by molding a ceramic to a honeycomb-like monolithic and, generally, is used to remove a particulate matter (hereinafter, referred to simply as a particulate) exhausted from the Diesel engine. During a drive of the Diesel engine, the particulate is progressively accumulated as the time has passed. If the accumulated quantity of the particulate is in excess of an allowance quantity, a filter clog occurs and exhaust (gas) pressure is raised so as to give an ill influence on a driveability. It is, therefore, necessary to remove the accumulated particulate at a regular time interval from the exhaust gas so as to prevent the filter clog from occurring.
A Japanese Patent Application First
Publication No. 2000-179326 published on Jun. 27, 2000 exemplifies a previously proposed regeneration method for a Diesel particulate filter in which the particulate is combusted and removed and by operating an engine control device such as injectors so that a temperature of the exhaust gas is raised up to a temperature value higher than that in an ordinary time and the particulate accumulated is heated up to a temperature equal to or higher than a combustion temperature. In the disclosed regeneration method, the exhaust gas temperature is raised from a time at which it is determined to be a time for the Diesel particulate filter to be regenerated to a time at which the particulate has combusted and its accumulation quantity has sufficiently been decreased so that it is expected that the Diesel particulate filter is deemed to have been regenerated. A target temperature of the exhaust gas to be reached to during this time period is set to a temperature such as 600° C. as high as a temperature required for an active combustion of the particulate. A method to raise the temperature of the exhaust gas to such a target temperature as described above is that injectors as the engine control device are operated on the Diesel engine in which a fuel injection is distributed a plurality of number of times and an injection timing of a post injection to be carried out after a main injection is retarded than that in the ordinary time.